Automatic vending machines are quite well known and are employed in just about every conceivable physical location such as, for example, factories, office buildings, institutional and education facilities, retail establishments, public gathering places, airport terminals, train stations, and the like. Automatic vending machines are utilized to vend a wide variety of items, including solid, as well as liquid based foodstuffs. Vending machines for vending liquid based foodstuffs such as hot and cold drinks, soup, and the like, typically offer a selection of foodstuff ingredients which may be combined with a liquid or selections wherein the liquid may be combined with one or more foodstuffs added in varying degrees of strength or concentration in accordance with the particular selection. For example, a coffee vending machine may offer black coffee, coffee with cream, coffee with sugar and cream, etc. As regards concentration, the machine may offer coffee with cream, coffee with extra or double cream, coffee with sugar, coffee with double sugar, and so forth.
The amount of each ingredient dispensed is conventionally controlled by cam operated switches which control the duration of energization of a dispensing device. For example, in locations in which it is required that an eight ounce drink is to be dispensed, the liquid is passed therethrough at a predetermined flow rate. By adjustment of the cam operated switch means, the valve may be energized, i.e., maintained in the open position, for an interval which is related to the flow rate so as to be sufficient to dispense the desired quantity of liquid. Similar cam operated switches are utilized to control the interval of energization during which powdered ingredient dispensing means are maintained operative to dispense the proper quantity of the powdered ingredient.
Typically, it becomes necessary to make adjustments in the cam operated switches in order to control the amount of the ingredient being dispensed to compensate for differences in dispensing devices, etc., and, although the cam assemblies are designed to be adjusted, such adjustments are quite difficult and require "cut and try" techniques before the proper adjustment is obtained, thus making maintenance and/or machine installation a tedious and complicated procedure.
The overall number of mechanical switches necessary to provide the desired number of selections further complicates the vending machine. In addition, mechanical switches of both the selection and cam operated type are subject to wearing, requiring added maintenance activity.